Massive study tests if daily pills can ward off diabetes

NCT ID NCT01633177

Completed Prevention Sponsor: Brigham and Women's Hospital Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This study looked at whether taking vitamin D or fish oil supplements every day can help prevent type 2 diabetes. Over 22,000 adults without diabetes took part. Researchers tracked who developed diabetes over time to see if the supplements made a difference.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: Vitamin D3 (cholecalciferol) and omega-3 fatty acids (fish oil)
What this could lead to: If it works, this could point toward a simple, low-cost way to help prevent type 2 diabetes using daily supplements.
What could go wrong: This is a large, completed trial, but supplements may not reduce diabetes risk as hoped. Results may show no benefit or only a small effect.

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Conditions

The condition(s) this trial relates to.

Insulin Resistance type 2 diabetes mellitus prevention target

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

TYPE 2 DIABETES

Contacts and locations

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Locations

Division of Preventive Medicine, Brigham and Women's Hospital

Boston, Massachusetts, 02215, United States

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